In order to subject several moving parts to computerized control, it has been conventional practice in the past to give commands on the basis of a stored program, check to see, at intervals of, e.g., a hundredth of a second, that each of the moving parts has moved punctually to a prescribed position, and answer for trouble-free operation by generating a correcting signal when there is something amiss.
In prior art, only the moving parts connected to servomechanisms such as servomotors can be subjected to the correction of speed, etc. Even if each of the moving parts can afford to develop a higher speed, the time required for going through all the processes cannot be shortened. This is because time is required for checking to see that each of the moving parts has moved in strict accordance with a command.
In case where all the moving parts are adapted to be actuated in movement by respective cams mounted on a single camshaft driven by means of a motor such as a general-purpose motor in which rotational speed is directly related to voltage, the prior art has never provided an effective way of connecting these moving parts to servomotors for the purpose of computerized control.